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I received a set of aerial images taken with a Canon camera, I don´t know which kind of lens it has, or if it has been modified.

After performing split image algorithm in Qgis, I get four new files: split_0, split_1, split_2 and split_3.

How many bands are in the original image, and how do I determine which file corresponds to which band?

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    Have you tried gdalinfo on the original (before the split)? – Richard Law Jan 5 '16 at 1:38
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    Depending on the sensor it's likely to be NIR, R, G and B but could just as easily be FIR, NIR, G and B but not necessarily in that order... NIR = Near InfraRed, FIR = Far InfraRed. Personally I'd look into whatever metadata / product statements that came with the image and if none were supplied track down the supplier/source and ask them politely. If you cannot tell at all then you can compare band combinations to (for example) Google - RGB will look fairly close and any infrared bands will look slightly 'funny', though that would have to be a very last resort and not definitive. – Michael Stimson Jan 5 '16 at 2:59
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    Agreed @MichaelMiles-Stimson, likely nIR, R, G, B. If this is a handheld camera without much info, you'll need to use principles of spectral remote sensing to determine which bands are which. For example, nIR is absorbed almost completely by water and will therefore have a DN of ~0 along water features. – Aaron Jan 5 '16 at 4:23
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Your image is likely composed of near-infrared (nIR), red, green, and blue spectral bands (i.e. 4 total). If this is a handheld camera without much metadata, you'll need to use principles of spectral remote sensing to determine which spectral bands are which. For example, nIR is absorbed almost completely by water and will therefore have a digital number (DN) of ~0 along water features. Blue is largely reflected off water and will have the highest DN value over water. Red is absorbed by healthy green vegetation and will likely have the lowest DN value for vegetation (Figure 1). Green and nIR wavelengths are reflected by healthy green vegetation, however, the nIR wavelength will have a higher reflectance than green, which will be second highest.

To recap:

  • nIR will have the highest DN over vegetation and the lowest DN over water
  • Red will have the lowest DN over vegetation
  • Blue will have the highest DN over water
  • Green will have the second highest DNs over vegetation

Figure 1. enter image description here

Source: https://science.nasa.gov/ems/08_nearinfraredwaves

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